To determine the role of the transmucosal potential difference in the transport of water and electrolyte across the mucosa of the stomach, small and large bowel using the in vivo voltage clamp apparatus and technique devised and validated recently in our laboratory. To determine whether fatty acids can act as carriers of Na and H ions in their transport across the mucosa of the small bowel as they have been found to do in the transport of Na and H ions across the mucosa of the stomach.